Effects Of Land Uses On Soil Organic Carbon Stock In Alpine Meadow In The Eastern Qilian Mountain Area

Alpine meadow is the main ecosystem in the Qinghai-Tibet Plateau, the soil organic carbon changes under different land-use patterns of which are closely related to ecosystem pattern, human activities and climate change. A typical Alpine meadow of pasturing area in the Eastern Qilian mountain was selected, the contents of soil organic carbon (SOC), soil organic carbon density, soil organic carbon pool, particulate organic carbon (POC), light fraction organic carbon (LFOC), carbohydrate were determined on-site under different land uses types and topography, to study effects of land uses change and topography on them, this study aimed to provide reasonable advices for human activities in alpine meadow area, such as grazing and traveling, and provide scientific advices for ecological restoration under the situation of land deterioration. The main conclusions were showed as following:1. In alpine meadow area, the soil organic carbon content varied in different land-use type, the content of SOC can be listed as arboreal lands> shrub land> meadow> bare land. There was an apparent vertical hierarchy characteristic of the contents of SOC, soil organic carbon density, and soil carbon pool under different land uses types. In surface soil of0～20cm, the content of SOC was higher than those other land uses. But in the soil layer of20～60cm, the contents of soil organic carbon of arboreal lands and shrub land were higher than those in other land uses.2. There was an apparent vertical hierarchy characteristic of the contents of particulate organic carbon, light fraction organic carbon and carbohydrate under different land uses types and topography.3. As to slope aspect, the soil organic carbon density and organic carbon pool in the semi-southward slope were higher than those in semi-northward slope. The topography affected the soil organic carbon content significantly. 4. Organic carbon pool can be listed as meadow soil> shrub land> arboreal lands> bare land. And the meadow and shrub land were the main soil organic carbon pools in the meadow area. The degradation of meadow will decrease in the content of soil organic carbon apparently.5. In the meadow area, change in the particle organic carbon, light fraction organic carbon and carbohydrate contents were sensitively related to land use change. In three kinds of the active organic carbon types, the carbohydrates could impressible reflect the change of land uses change, but the sensitivity degree of light fraction organic carbon to reflect the change of land uses was a bit weaker than others.In conclusion, the soil organic carbon contents were different under different land uses types with an apparent vertical hierarchy characteristic. Meadow degradation will cause the substantial reduction of soil organic carbon content. The three kinds of active organic carbon, the particle organic carbon, light fraction organic carbon and carbohydrate significantly related the land use change. Rational grazing, vegetation restoration, rational management of pasture and land use types, were the win-win ways to increase in soil organic carbon content, for the protection of the natural systems and sustainable development in the meadow area, especially for the fragile area in the Eastern Qilian Mountain region.